1. Technical Field
The invention relates to an image processing system, an image processing method, a computer readable medium storing an image processing program, and a data signal, which can make color conversion of a color image. Particularly, it relates to an image processing system programmed on a computer-readable medium, an image processing program and an image processing method suitable for use in a color proof system.
2. Description of the Related Art
A so-called color proof system in which a trial proof obtained by simulating a print color with using a simplified color printer (such as an electrophotographic printer or an ink-jet printer) is output so that color proofreading is performed on the basis of the trial proof in a process before a printed matter is formed by a press (such as a rotary press for forming a final printed matter) has been used in the color printing trade in recent years.
To perform color proofreading by using such a color proof system, a color reproducible by a press needs to be reproduced by a color printer. Incidentally, the printing press and the color printer are print output devices different from each other, so that the printing press and the color printer are different from each other in device-dependent color characteristic. Therefore, a combination of colorimetric data obtained by measuring a color chart of color patches output from the printing press and CMYK data corresponding to the colorimetric data and a combination of colorimetric data obtained by measuring a color chart output from the color printer and CMYK data corresponding to the colorimetric data are used in the color proof system when color proofreading is performed. A printing press color profile is generated from the combination of colorimetric data and CMYK data with respect to the printing press whereas a printer profile is generated from the combination of colorimetric data and CMYK data with respect to the color printer. The printing press color-dependent CMYK data used for color proofreading are converted into a device-independent color space, such as an XYZ color space or an L*a*b* color space defined by CIE (Commission International de l'Eclairage), by the printing press color profile and then further converted into color printer-dependent CMYK data by the printer profile. In this manner, a color proof sample approximate to the printing press color generated by the printing press can be obtained by the color printer. Accordingly, the printing press color generated by the printing press can be simulated by the color printer, so that simple color proofreading can be performed before pressing is made by the printing press.